Topic
Brillouin zone
About: Brillouin zone is a research topic. Over the lifetime, 13849 publications have been published within this topic receiving 383077 citations.
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TL;DR: In this article, the authors used first-order Raman scattering to determine the zone-center phonons and their dependence on structural attributes such as stress, chemical composition, impurities, and doping.
Abstract: We present a selection of our contributions to basic research on the lattice dynamical properties of groupIII nitrides and their alloys. We used first-order Raman scattering to determine the zone-center phonons and their dependence on structural attributes such as stress, chemical composition, impurities, and doping. Results on the angular dispersion of the polar modes, strain distribution, coupled LO-phonon plasmon modes, multi-mode behavior in AlxGa1–xN, and the quantitative determination of the phase purity of cubic and hexagonal GaN are shown. Second-order Raman-scattering experiments on GaN and AlN provide information on the vibrational states throughout the entire Brillouin zone. Based on a comparison of experimental data and calculated phonon-dispersion curves we assigned the observed structures to particular phonon branches and points in the Brillouin zone. We also discuss the behavior of the optical modes under large hydrostatic pressure.
79 citations
TL;DR: The heat capacity at room temperature and the Debye temperature within the LDA are in better agreement with the experimental results, and one can obtain the important mechanical and thermal properties of materials.
Abstract: Elastic and thermal properties of the TiO2 lattice in anatase and rutile phases were studied in the framework of density functional perturbation theory within the local density approximation (LDA) and generalized-gradient approximation (GGA) The full elastic constant tensors of the polymorphs were calculated by linear fits to the acoustic branches of the phonon band structure near the center of the first Brillouin zone in symmetry directions of the crystals It was observed that the elastic constants within the GGA are in better agreement with experiment In addition, the Born effective charges, dielectric tensor, heat capacity, mean sound velocity and Debye temperature were calculated The heat capacity at room temperature and the Debye temperature within the LDA are in better agreement with the experimental results Therefore, using the phonon band structure and the density of states, one can obtain the important mechanical and thermal properties of materials
79 citations
TL;DR: In this article, a modified Monkhorst-Pack (MMP) special points meshes for cubic crystals are proposed for Brillouin zone integration, which ensure the higher precision of the points summation and faster and regular convergence of the results of the self-consistent calculations of the electronic structure of crystals.
Abstract: Modified Monkhorst-Pack (MMP) special points meshes for Brillouin zone integration are proposed for cubic crystals. The MMP meshes suggested ensure the higher precision of $\mathbf{k}$-points summation and faster and regular convergence of the results of the self-consistent calculations of the electronic structure of crystals. The efficiency of MMP meshes is demonstrated by DFT-GGA (density functional theory - generalized gradient corrections) calculations of $\mathrm{SiC}$ crystal.
79 citations
TL;DR: In this article, the lattice distortion accompanying the introduction of a solute depends on the difference in size of the solute and solvent atoms, their relative electronegativity and the electron : atom ratio in the solution.
Abstract: Accurate measurements have been made of the lattice spacings in binary magnesium solid solutions containing aluminium, bismuth, cadmium, indium, lead, lithium, silver, tin and zinc. The results show that the lattice distortion accompanying the introduction of a solute depends on the difference in size of the solute and solvent atoms, their relative electronegativity and, where the valency of the solute differs from that of magnesium, the electron : atom ratio in the solution. Where the solute is not divalent, variation of the number of electrons in the conduction band seems to be entirely associated with the c dimension of the lattice, in such a way that a regular increase in axial ratio takes place as the electron concentration increases. The manner in which this affects the accepted picture of the distribution of electrons in the Brillouin Zones of magnesium is discussed.
79 citations
TL;DR: In this paper, a double-beam, single-detector wavelength-modulation system was used to obtain unambiguous line shapes for the real and imaginary part of the dielectric constants, permitting the identification of the types of critical points involved in an optical transition, and the determination of the existence of hyperbolic exciton interactions.
Abstract: The band structures of Ge, Si, GaAs, GaP, GaSb, InAs, InP, InSb, and AlSb have been studied in reflectivity in the energy region 1.6-5.0 eV at temperatures ranging from 80 to 300 \ifmmode^\circ\else\textdegree\fi{}K. Utilizing a double-beam, single-detector wavelength-modulation system, and ensuing Kramers-Kr\"onig analyses, experimentally unambiguous line shapes have been obtained for the real and imaginary part of the dielectric constants, permitting the identification of the types of critical points involved in an optical transition, and the determination of the existence of hyperbolic exciton interactions. Such an interaction has been verified in all materials, except Si, as an ${M}_{1}$ critical point located at $\ensuremath{\Lambda}$ in the Brillouin zone. The location and energy of the interband transition in these semiconductors correlates with existing band calculations. The interband transitions in Si are dominated by structure from a large region of the Brillouin zone. The high-energy ${E}_{2}$ transitions in all materials give evidence of a multiplicity of critical-point structure.
79 citations